I set up some relatives with a Linksys cable modem router on their Comcast connection. It is the WRT54G2 V1.5. As soon as we connect the computer directly to the cable modem the speed increases by a hell of alot. I have WPA encryption enabled with a long password; a few sports figures names and a massive number - 20 characters and impossible to guess; so I don't see how anyone can be using it illegally.
Could the router be bad?